A process, such as the Programmable Adaptive Inkjetting of Nanoscale Thin-Films (PAINT) process, is utilized for depositing films of tailored thickness at near-zero material wastage. PAINT is substantially agnostic towards the choice of substrate type, thickness or material and is capable of depositing films over large areas. By design, PAINT can also substantially decouple the influence of systematic parasitics, such as surface topography, inkjet drop volume variation, etc., and prevent them from corrupting the final film thickness.
However, in such a process, when the surface of the substrate is of primary importance, such as in planarization, surface profile metrology is needed to obtain a map of nominal and parasitic topography on the substrate. The surface profile metrology needs to measure the topography of the final surface closest to the “superstrate” (utilized for urging liquid organic material drops that were dispensed by an inkjet to merge laterally across the substrate) just prior to the execution of the PAINT process.
Any mismatch in coordinate frames between the substrate and the reference surface, and subsequently between the substrate and the superstrate, or the substrate and the inkjet may result in unwanted parasitic signatures. This overall alignment typically ensures that the drop deposition and any subsequent PAINT are performed on the correct locations. Tolerable errors in alignment depend on the nature of the substrate nominal figure and the amount of correction desired in a single PAINT step. Typically these errors may need to be <100 μm, <50 μm, <10 μm or <1 μm.
As a result, it becomes necessary to establish proper alignment, especially of the substrate coordinate system relative to the inkjet coordinate system. The location and orientation of all coordinate systems, i.e., substrate coordinate system, metrology coordinate system and the inkjet coordinate system, need to be known with micron-scale precision (depends on application and may need to be <100 μm, <50 μm, <10 μm or <1 μm) relative to the global stage coordinate system. It is important to minimize the introduction of parasitic topography errors coming from misalignment between the actual substrate topography and the topography that is corrected by the inkjet.
Currently though, no techniques exist for minimizing the introduction of such parasitic topography errors.